Headlight-lens.



D. FOSTER.

HEDLIGHT LENS.

APNIC/mora min APR. 23,1917.

l'a Patented Nov. 11, 19m.

- /NvENToR @mw we Rw-TM citi'zen of the United States,

' respectively,

oline forwardly UNITED STAT-ns PATENT onirica.;

DONOVAN FOSTER., or SEATTLE, WASHINGTON, -AssIGNOa TO FOSTER.'D'TVELOPMENT- CO., 0F SEATTLE, WASHINGTON,

A CORPORATION or WASHINGTON.

HEADLIGnT-Lnns.

TaaZZ whom t may concern Beit known that I, DONOVAN Fos'rnR, a

residing at Seattle, in the county of King and State of Washington, haveinvented certain new. an useful Improvements in Headlight-Lenses, of'which the following is a specification.

This invention relates to lenses, and has articular reference to thelenses of automobile headlights. The object of my invention is toproduce a lens Ofthis character which will refract in a desired eneraldirection, practically all of the light rays from the lamp, andeliminate the glare which is at least a serious inconvenience topedestrians and othersl In carrying out my inventiOn,-I provide a lenshaving' on its outer or front face aplurality of peculiarly formedprisms which co- Operativel serve to direct -the light rays downwarlyand in horizontally divergi'ng directions.

The invention is illustrated in the aceoma, panying drawings, in whichu,

Figure 1 is a front elevational view of the lens. Figs. 2 and 3 aresectional views taken through 2-2 and 3--3 of Fi .1. Fig. 4 is avertical section of a hea ight reflector withvmy improved lens applied'thereto, and representing, by. broken 'lines the directions-- of the'reflector light rays emanating from the headlight, and by full linestheir directions as modified-by my improved lens. Fig.

5 is a horizontal section` of the device shown in Fig. 4 and in which is.illustrated diagrammatically by unbroken andvbroken' lines, thedirections of the light rays with and without the use of mylens.

Referring to the drawings, a lens is desha'pe having a seriis'ofsuperposed prismss'urrounded, preferably, by a peripheralrim portion 11whereby the lensmay be secured.'u to-V-lthe mouth of a reflector 12 byvany lusual oitsuitable fastening devices The upper lens prism .A isp,provided in front with two plain surfaces. 1 and 131 ei:-tendinglaterally from a m ial verticalr. plane indicated by line 14, anddiverge therefrom in angular relations toward the rear.4 These prismsurfaces 13-. .7131 moreover, in?

fronitop to bottom and' mak'eacute angles', as at 15, with the `prismsunder surfacel which, asshozwnxis located Ordinarily, the vraysupwardly, glare in headlights Speeicatlon Of letters Patent. PatentedNOV, 11, 1919;. Application flied April 23, 1917.'. serial No. 163,850.

B slopes from the rear of the under surface! '16 of the prism A to, anapex 18 with an under surface 19 and from the rear of the latter thelower prisms front surface -2O slopes forwardly to its apexwith theunder edge 21. The inclinations of the under Sur. z

faces 1 6l and I19 of prisms A and B corre-- spond to or aresubstantially parallel with the directions in which the light rays", -asin, dicated by@ and b, are refracted in pass.'v ing through therespective prisms so as not to sacrifice any .light values due 'tototal-' I reflection by the bases, or under surfaces of the respectiveprisms. v I l The surfaces 17 and 20 of the respective prisms B and Cmay, if desired, be made Q slightly convex horizontally, as illustratedin Fig. 3 with respect to prism B,

Centrally of the lens the pri vided with a notch 'having triangulanlyshaped 'side surfaces 22 arranged infangufsin A. is pro- 4lar relationssubstantially as shown in Figs. f

l' and 3,"and arranged to slope rearwardly' toward the vertical andhorizontal axes of the lens. f'

In a parabolic reiector, such` as" usuallemployed in` an automobileheadlight, ,the

rays derived from a Source of light at the I so-called inne-r focus aredirected upwardly ,A

` l R1, Fig. 4,' while the light rays Pley the lower portion of thereflector, as indicated by are by the upper portion ofthe. reflector jdirected downwardly Similarly, the rays of light indicated by R3 and'lt4 in Fig. 5 are reflected toward the left and ri ht, respectively,from the right and left sides of the reflector to cross at or about theaforesaid outer focus F1. A

are the cause of theobjectionahl` ent vent1on,1s Overcome by theprovision of a,. ens hav g PrSmatic elements whichA aonl meansuto not,only cause alLof the rays'to be directed downwardly, asi indiasindicated lby R?, .to` cross at or' aboutv what is conventionally knownas the' outer focus, -indicatedqby Fh; at a short distance infront ofthe headlight.

R1 which are thm'wii and which, by theA prescat edlbv'r1 and fr? in Fig.fi, but also serve'to direct Athe same laterallyfaa indicatedby r"l andr4 in Fig. 5 so that the referred-to outer focus is thereby advanced,resulting in the light bein thrown to better illuminate the road andfurther ahead than hitherto.

Due-to the sloping of the front surface of the prism A in two relativelyinclined planes 13j-131Y and'.by the provision of laterally convexsurfaces 17 and 20 kfor the other prisms B and C, the raysare`furtherniore influenced to be spread horizontally and obviate theso-called spotting `The yrentrant vprism afforded. by the triangularsurfaces 22is located directly in front of the focus F, therebyrefracting to a greater extent than by the protrudiu prisms the directrays from the lamp, an

-causing such rays to be spreach. as indicated by r" in Fig. 5.

The front surface V13-131 of the upper prism A is 'inclined 'froma-vertical plane to al less extent than the front surfaces 17 and 2O ofthe lower prisms B and() to accordingly afford less refracting'power tothe upper prism and bending, so to speak, the rays into approximatelyparallel lines, and oliviating any vertical divergence of the light raysabove the longitudinal axis of the head? light and in front of theouterfocus.

-The operation and advantages of the invention will, it thought, beunderstood from the foregoing explanation.

1 .A lens having one-face formed to provide a series of transverseprisnisi whose front 'faces are arranged to refract down-V wardly allrays passing through the lens and whose under .faces are disposed'substantially parallelto sucli'refracted' rays, said lthrough the anglein center of thev lens, the frontface of said prism beingr formed in twovertical planes arranged in angular relations' with each other and alsosloping forwardly from the top tothe bottom, the under face ofz saidprism being inclined downwardly 'and forwardly from its juncture withthe front face of the adjacent prism.

3. A lens having one face formed with a series of protruding transverseprisms adapted to refract all light rays passing through the lens in adownward direction, said face of the lens being provided with a centralnotch formed of twotriangular plane surfaces arranged to retract therays of light passing through the lens directly from -a lamp in lateraldiverging directions. Y

4. A lens having a face provided with a plurality of transverseprismatic projections adapted to re-frac't downwardly all rays of lightpassing through the lens, and a notch formed of two'angular planesurfaces arranged;substantially centrally in the lens to refractzallrays passing through the angle directly from a light source in lateraldiverging directions. 5. A lens having its front surface formed with aprisimitic projecting portion of suhsta-ntially one-half the area of thelens, a notch provided vin said projecting portion at the center of thelower edge thereof, the front faces of said projecting portion and ofthe notch being arranged to retract the rays passing through the lens indownward and lateral directions. A

(3. A lens having one face formedto )rovide a series of transverseprisms wliose front faces are arranged to refract dowii wardly all rayspassing through the lens; said lens having a rentrant notch formed'.siihstantially centrally therein to refract all rays passing throughthe angledirectly from a light source in lateral diverging directions.

rDONOVANrosrnia.

